U-Boot的设备管理

目录

一、初始设备链表、初始化设备和注册设备
1.1 devices_init函数
1.2 devices结构的定义
1.3 drv_system_init 函数
二、设备注册
2.1 device_register (device_t * dev)
2.2 device_deregister(char *devname)
三、设备搜索

U-Boot通过devices_init函数创建设备链表，然后在devices_init函数中初始化设备并将设备添加到设备链表中。U-Boot使用devices_t结构体来管理设备，设备链表也就是devices_t结构体的链表。通过i2c_init、drv_lcd_init、drv_video_init、drv_keyboard_init、drv_logbuff_init、drv_system_init、serial_devices_init、drv_usbtty_init和drv_nc_init函数初始化设备(这些函数是否执行是通过宏来决定的)，并通过device_register函数注册设备。

一、初始设备链表、初始化设备和注册设备

U-Boot在第二阶段中通过devices_init函数创建设备链表，初始化设备并将其注册到设备链表中。该函数在common/devices.c文件中，其对应的头文件是nclude/devices.h。

1.1 devices_init函数

int devices_init (void){#ifndef CONFIG_ARM     /* already relocated for current ARM implementation */ulong relocation_offset = gd->reloc_off;int i;/* relocate device name pointers */for (i = 0; i < (sizeof (stdio_names) / sizeof (char *)); ++i) {stdio_names[i] = (char *) (((ulong) stdio_names[i]) +relocation_offset);}#endif/* Initialize the list */devlist = ListCreate (sizeof (device_t));//创建设备列表if (devlist == NULL) {eputs ("Cannot initialize the list of devices!\n");return -1;}#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)i2c_init (CFG_I2C_SPEED, CFG_I2C_SLAVE);//初始化i2c接口，i2c没有注册到devlist中去#endif#ifdef CONFIG_LCDdrv_lcd_init ();#endif#if defined(CONFIG_VIDEO) || defined(CONFIG_CFB_CONSOLE)drv_video_init ();#endif#ifdef CONFIG_KEYBOARDdrv_keyboard_init ();#endif#ifdef CONFIG_LOGBUFFERdrv_logbuff_init ();#endifdrv_system_init ();//这里其实是定义了一个串口设备，并且注册到devlist中#ifdef CONFIG_SERIAL_MULTIserial_devices_init ();#endif#ifdef CONFIG_USB_TTYdrv_usbtty_init ();#endif#ifdef CONFIG_NETCONSOLEdrv_nc_init ();#endifreturn (0);}

经过devices_init()，创建了devlist，但是只有一个串口设备注册在内。

1.2 devices结构的定义

/* Device information */typedef struct {intflags;/* Device flags: input/output/system*/intext;/* Supported extensions*/charname[16];/* Device name设备名称*//* GENERAL functions 启动和停止函数 */int (*start) (void);/* To start the device*/int (*stop) (void);/* To stop the device*//* OUTPUT functions 输出函数 */void (*putc) (const char c);/* To put a char*/void (*puts) (const char *s);/* To put a string (accelerator)*//* INPUT functions  输入函数*/int (*tstc) (void);/* To test if a char is ready...*/int (*getc) (void);/* To get that char*//* Other functions */void *priv;/* Private extensions*/} device_t;

1.3 drv_system_init 函数

drv_system_init 函数初始化串口设备，源码如下：

static void drv_system_init (void){device_t dev;//定义一个结构体memset (&dev, 0, sizeof (dev));//为刚刚定义的结构体分配内存strcpy (dev.name, "serial");//名称dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM; #ifdef CONFIG_SERIAL_SOFTWARE_FIFOdev.putc = serial_buffered_putc;dev.puts = serial_buffered_puts;dev.getc = serial_buffered_getc;dev.tstc = serial_buffered_tstc;#elsedev.putc = serial_putc;dev.puts = serial_puts;dev.getc = serial_getc;dev.tstc = serial_tstc;#endifdevice_register (&dev);//注册函数#ifdef CFG_DEVICE_NULLDEVmemset (&dev, 0, sizeof (dev));strcpy (dev.name, "nulldev");dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;dev.putc = nulldev_putc;dev.puts = nulldev_puts;dev.getc = nulldev_input;dev.tstc = nulldev_input;device_register (&dev);#endif}

二、设备注册

有连个设备注册函数，一个的参数时devces结构体，另一个的参数是设备的名称

2.1 device_register (device_t * dev)

设备注册，将结构体添加到devlist的后面，device_register函数的源码如下：

int device_register (device_t * dev){ListInsertItem (devlist, dev, LIST_END);return 0;}

/*******************************//* * returns 1 if the item is inserted, returns 0 if out of memory or * bad arguments were passed. */int ListInsertItem (list_t list, void *ptrToItem, int itemPosition){return ListInsertItems (list, ptrToItem, itemPosition, 1);}/*******************************/int ListInsertItems (list_t list, void *ptrToItems, int firstItemPosition,     int numItemsToInsert){int numItems = (*list)->numItems;if (firstItemPosition == numItems + 1)firstItemPosition = LIST_END;else if (firstItemPosition > numItems)return 0;if ((*list)->numItems >= (*list)->listSize) {if (!ExpandListSpace (list, -numItemsToInsert))return 0;}if (firstItemPosition == LIST_START) {if (numItems == 0) {/* special case for empty list */firstItemPosition = LIST_END;} else {firstItemPosition = 1;}}if (firstItemPosition == LIST_END) {/* add at the end of the list */if (ptrToItems)memcpy (ITEMPTR (list, numItems), ptrToItems,(*list)->itemSize * numItemsToInsert);elsememset (ITEMPTR (list, numItems), 0,(*list)->itemSize * numItemsToInsert);(*list)->numItems += numItemsToInsert;} else {/* move part of list up to make room for new item */memmove (ITEMPTR (list, firstItemPosition - 1 + numItemsToInsert), ITEMPTR (list, firstItemPosition - 1), (numItems + 1 - firstItemPosition) * (*list)->itemSize);if (ptrToItems)memmove (ITEMPTR (list, firstItemPosition - 1), ptrToItems, (*list)->itemSize * numItemsToInsert);elsememset (ITEMPTR (list, firstItemPosition - 1), 0,(*list)->itemSize * numItemsToInsert);(*list)->numItems += numItemsToInsert;}return 1;}

2.2 device_deregister(char *devname)

int device_deregister(char *devname){int i,l,dev_index;device_t *dev = NULL;char temp_names[3][8];dev_index=-1;for (i=1; i<=ListNumItems(devlist); i++) {dev = ListGetPtrToItem (devlist, i);if(strcmp(dev->name,devname)==0) {dev_index=i;break;}}if(dev_index<0) /* device not found */return 0;/* get stdio devices (ListRemoveItem changes the dev list) */for (l=0 ; l< MAX_FILES; l++) {if (stdio_devices[l] == dev) {/* Device is assigned -> report error */return -1;}memcpy (&temp_names[l][0],stdio_devices[l]->name,sizeof(stdio_devices[l]->name));}ListRemoveItem(devlist,NULL,dev_index);/* reassign Device list */for (i=1; i<=ListNumItems(devlist); i++) {dev = ListGetPtrToItem (devlist, i);for (l=0 ; l< MAX_FILES; l++) {if(strcmp(dev->name,temp_names[l])==0) {stdio_devices[l] = dev;}}}return 0;}

三、设备搜索

/* search a device */device_t *search_device (int flags, char *name){int i, items;device_t *dev = NULL;items = ListNumItems (devlist);if (name == NULL)return dev;for (i = 1; i <= items; i++) {dev = ListGetPtrToItem (devlist, i);if ((dev->flags & flags) && (strcmp (name, dev->name) == 0)) {break;}}return dev;}